Meta-analysis of GWAS on both Chinese and European populations identifies GPR173 as a novel X chromosome susceptibility gene for SLE.

BACKGROUND: Systemic lupus erythematous (SLE) is a complex autoimmune disease with female predominance, particularly affecting those of childbearing age. We performed analysis of three genome-wide genotyping datasets of populations of both Chinese and European origin.

METHODS: This study involved 5695 cases and 10,357 controls in the discovery stage. The lead signal on chromosome X was followed by replication in three additional Asian cohorts, with 2300 cases and 4244 controls in total. Conditional analysis of the known associated loci on chromosome X was also performed to further explore independent signals.

RESULTS: Single-nucleotide polymorphism rs13440883 in GPR173 was found to be significantly associated with SLE (Pmeta  = 7.53 × 10- 9 , ORmeta = 1.16), whereas conditional analysis provided evidence of a potential independent signal in the L1CAM-IRAK1-MECP2 region in Asian populations (rs5987175 [LCA10]).

CONCLUSIONS: We identified a novel SLE susceptibility locus on the X chromosome. This finding emphasizes the importance of the X chromosome in disease pathogenesis and highlights the role of sex chromosomes in the female bias of SLE.